Drilling Minute – PDC Bit Overview

Ever since prehistoric times, mankind has built millions of tools used to make holes. But is there one bit to rule them all? In this Drilling Minute, we’ll discuss the most prevalent type of oil & gas drill bit today – the PDC drill bit.

It has been known for a long time that shearing is the most efficient way to fail most rock types. But for most of that time, the cutting elements and materials available to cut the rock were either too small or would wear down too fast to drill economically… Then came PDC.

What is a PDC Bit?

The focal point of a PDC bit is the polycrystalline diamond cutters, which is where it gets its name. The cutters are usually cylinders with a man-made, black diamond cutting face engineered to withstand the extreme abrasion, impact, and heat that comes from drilling through rock.

Cutting Structure

The PDC cutters are arranged into a 3D geometry called the cutting structure. The cutting structure may seem simple, but it is often the most complex part of a PDC bit design and usually drives the bit’s performance.

Cutter Arrangement

In order for a PDC bit to function reliably, the cutting structure has to remain intact. For this reason, the cutters are usually aligned into rows, allowing the cutting structure to be held together by large blades. The blades also define passageways for the drilling fluid known as junk slots.

Bit Body

The blades are a part of the bit body, which connects the cutting structure to the drill string. PDC bit bodies are all made of steel at the pin connection and transition to a tungsten carbide-composite material on the outer surfaces. The bit bodies are referred to as matrix or steel depending on how they are manufactured and how much tungsten carbide is used.

Matching your Drilling Application

PDC bits can be designed with a nearly infinite combination of variables, customized for the unique needs of different and changing drilling applications. Today, almost 90% of the drill bits used in oil and gas drilling are PDCs.

While bit design is critical, no PDC bit can function without PDC cutters, which is the topic of the next Drilling Minute.

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